1. Technical Field
The present invention relates to a vehicular headlamp that forms a luminous intensity distribution pattern for a low beam by irradiating light from a plurality of lamp piece units, each of which constitutes a light source by a semiconductor light emitting element.
2. Related Art
In the related art, a vehicular headlamp is able to form a luminous intensity distribution pattern for a low beam having a cutoff line at an upper end edge thereof, to ensure front recognizability of a driver of one's own car as much as possible while preventing the casting of glare to a driver of a car running on the opposite side or the like.
In such a case, Japanese publication JP-A-2003-123517 describes a vehicular headlamp constituted to form a luminous intensity distribution pattern for low beam by irradiating light from a plurality of lamp piece units each constituting a light source by a semiconductor light emitting element.
Further, Japanese publications JP-A-2003-31007 and JP-A-2003-31011 describe a vehicular lamp piece of a parabolic pillar type constituted to reflect light from a plurality of semiconductor light emitting elements linearly aligned in a horizontal direction to a front side of the lamp piece by a reflector including a reflecting face comprising a curved face in a shape of a parabolic pillar.
By adopting the lamp piece constitution described in JP-A-2003-123517, thin formation of the vehicular headlamp can be achieved in the related art. In such a case, when the vehicular lamp piece of the parabolic pillar type described in JP-A-2003-31007 and JP-A-2003-31011 is adopted as a lamp piece unit, a luminous intensity distribution pattern prolonged sideways can be formed to enable formation of a wide diffusing region of the luminous intensity distribution pattern for the low beam.
However, in a number of related art vehicular headlamps, a shape of surface thereof is formed to flex to a rear side from an inner side of a vehicle width direction to an outer side in the vehicle width direction. Therefore, when the vehicular lamp piece of the parabolic pillar type described in JP-A-2003-31007 or JP-A-2003-31011 is adopted as the lamp piece unit in a lamp piece constitution in which a plurality of lamp piece units are arranged simply to direct to a front direction of a vehicle as in the vehicular lamp piece described in JP-A-2003-123517, the following related art problem occurs.
When the lamp piece unit of the parabolic pillar type is arranged to direct to the front direction of the vehicle in the vehicular headlamp having the surface shape flexed to the rear side, there is a related art problem in that a portion of diffused and reflected light from the reflector is blocked by other lamp piece constituting member and the luminous intensity distribution pattern prolonged sideways cannot be formed.
Further, the lamp piece unit of the parabolic pillar type is provided with an outer shape which is angular as a whole. Therefore, when the lamp piece unit is arranged to direct to the front direction of the vehicle in the vehicular headlamp having the surface shape flexed to the rear side, a large space in the depth direction is needed for arranging the lamp piece unit. Therefore, there is a related art problem in that the ability to achieve thin formation of the lamp piece by adopting the semiconductor light emitting element as the light source is reduced.